1. Field of the Invention
The present invention relates to the design of ring gear/pinion gear drive gear-sets for heavy-duty drive axles and more particularly, to the design of a family or series of such gear-sets comprising a single ring gear design utilizable with any one of a series of specially designed pinion gears, each member of the series utilizing a pinion gear having a different number of teeth.
2. Description of the Prior Art
Right angle drive trains for heavy duty drive axles utilizing pinion gear/ring gear gear-sets are well known in the prior art, as may be seen by reference to U.S. Pat. Nos. 3,265,173; 4,018,097; 4,046,210; 4,050,534 and 4,263,834, the disclosures of which are hereby incorporated by reference. Such gear-sets are usually of the well known spiral bevel or hypoid gear type.
It is also well known to design a series or family of gear-sets, having a similar torque capacity, but different ratios. For example, a well know series of prior art drive axles utilizes a series of pinions each having a different number of teeth (i.e. 6, 7, 8 and 9) for meshing engagement with a series of ring gears having a given pitch diameter (i.e. 161/2 inch) and number of teeth (i.e. 39) to provide a plurality of input shaft to output shaft ratios (6.50:1; 5.57:1; 4.88:1 and 4.33:1).
In designing such a series or family of gear-sets, each individual ratio utilized a unique ring gear specially designed to properly mesh with a particular specially designed pinion. Properly meshing involves running with a minimum of noise, for an acceptable period of time under a rated load in both the driving and driven (i.e. drive and coast) modes of operation. For example, the 39 tooth ring gear designed to properly mesh with the 7 tooth pinion (i.e. the "7/39" ring gear) was different from the 39 tooth ring gear designed to properly mesh with the 8 tooth pinion (i.e. the "8/39" ring gear) and would not properly mesh with the 6, 8 or 9 tooth pinions.
While the individual gear-sets of the family or series of ring gear/pinion gear gear-sets of the prior art operated in a very acceptable manner, such a method of designing and manufacturing gear-sets was not ecomonically desirable, especially as to the relatively larger more costly ring gears, in the volumes and variety of sizes and ratios associated with heavy-duty drive axles (i.e. drive axles utilized with heavy-duty trucks, off-the-road construction vehicles and the like.)